Several important natural substances are chelates. In chelates a central metal ion is bonded to a large organic molecule, a molecule composed of carbon, hydrogen, and other elements such as oxygen and nitrogen. One such chelate is chlorophyll, the green pigment of plants. In chlorophyll the central ion is magnesium, and the large organic molecule is a porphyrin. The porphyrin contains four nitrogen atoms that form bonds to magnesium in a square planar arrangement. There are several forms of chlorophyll including, for example, chlorophyll a.
Chlorophyll is one of the most important chelates in nature. It is capable of channeling the energy of sunlight into chemical energy through the process of photosynthesis. During photosynthesis, the energy absorbed by chlorophyll transforms carbon dioxide and water into carbohydrates and oxygen. The chemical energy stored by photosynthesis in carbohydrates drives biochemical reactions in nearly all living organisms.
In the photosynthetic reaction, carbon dioxide is reduced by water whereby electrons are transferred from water to carbon dioxide. Chlorophyll assists this transfer. When chlorophyll absorbs light energy, an electron in chlorophyll is excited from a lower energy state to a higher energy state. In this higher energy state, this electron is more readily transferred to another molecule. This starts a chain of electron-transfer steps, which ends with an electron transferred to carbon dioxide. Meanwhile, the chlorophyll, which gave up an electron can accept an electron from another molecule. This is the end of a process, which starts with the removal of an electron from water. Thus, chlorophyll is at the center of the photosynthetic oxidation-reduction reaction between carbon dioxide and water.
There is a need for a photographic imaging apparatus, which utilizes a photosensitive agent capable of producing oxygen when exposed to light. There is a further need for a photographic imaging apparatus that is more environmentally friendly, cost efficient to implement, and relatively simple to make and use.